The present invention relates to an improved X-ray tube apparatus having an evacuated cylindrical metal envelope, anode and cathode electrodes and high voltage leads for the electrodes which are disposed at the frontal or end surfaces of the X-ray tube. In particular, the invention relates to an X-ray tube of the type described in which the effects of secondary electron emission are minimized by providing shielding electrodes.
In U.S. Pat. No. 4,126,803, granted Nov. 21, 1978 and assigned to the same assignee as the present invention, there is described an X-ray tube of the type having a sealed cylindrical vacuum envelope with the high voltage leads for the anode and cathode extending through the end surfaces of the envelope. The envelope includes a metal cylindrical wall member which is sealed in a vacuum-tight manner at both ends by respective end members with at least one of the end members being an annular ceramic member whose outer periphery is fastened to the cylindrical member in a vacuum-tight manner and through whose central opening passes one of the high voltage leads, and possibly other required leads, in a vacuum-tight manner, so that the insulating path between the associated high voltage lead and the cylindrical member is predominantly in a radial direction. Preferably the outer surface of the annular ceramic member forms an angle with a plane perpendicular to the longitudinal axis of the tube which is equal to or less than 45.degree., and in particular equal to or less than 30.degree..
U.S. Pat. No. 4,126,803 is incorporated herein by reference and forms a part of the present specification.
It is an object of the present invention to provide an apparatus including an X-ray tube which is of a compact and space saving design and has improved high voltage stability.